diff --git a/behavior/arrival/arrival_sequence.v b/behavior/arrival/arrival_sequence.v
index 790ee3be07a1bb931fa2d58f968d69918b573144..1945a595854ea2c3d8bcd6c1e649298da314e795 100644
--- a/behavior/arrival/arrival_sequence.v
+++ b/behavior/arrival/arrival_sequence.v
@@ -39,8 +39,8 @@ End JobProperties.
Class JobArrival (J : JobType) := job_arrival : J -> instant.
-(* Next, we define properties of a valid arrival sequence. *)
-Section ArrivalSequenceProperties.
+(* Next, we define valid arrival sequences. *)
+Section ValidArrivalSequence.
(* Assume that job arrival times are known. *)
Context {Job: JobType}.
@@ -59,10 +59,15 @@ Section ArrivalSequenceProperties.
jobs at any given time. *)
Definition arrival_sequence_is_a_set := forall t, uniq (jobs_arriving_at arr_seq t).
-End ArrivalSequenceProperties.
+ (* We say that the arrival sequence is valid iff it is a set and arrival times
+ are consistent *)
+ Definition arrival_sequence_is_valid :=
+ arrival_times_are_consistent /\ arrival_sequence_is_a_set.
+
+End ValidArrivalSequence.
(* Next, we define properties of job arrival times. *)
-Section PropertiesOfArrivalTime.
+Section ArrivalTimeProperties.
(* Assume that job arrival times are known. *)
Context {Job: JobType}.
@@ -83,7 +88,7 @@ Section PropertiesOfArrivalTime.
some time t with t1 <= t < t2. *)
Definition arrived_between (t1 t2 : instant) := t1 <= job_arrival j < t2.
-End PropertiesOfArrivalTime.
+End ArrivalTimeProperties.
(* In this section, we define arrival sequence prefixes, which are useful to
define (computable) properties over sets of jobs in the schedule. *)